A number of standards that define digital display interfaces of a digital audio/video interconnect are discussed in the related art. One example for such a standard is the high-definition multimedia interface (HDMI) which is a compact audio/video connector interface for transmitting uncompressed digital streams. The HDMI connects a digital multimedia (or audio/video) source (e.g., a set-top box, a DVD player, a personal computer, a video game console, etc.) to a compatible digital sink, such as a digital television.
DisplayPort™ (or DP) is another example for a standard that defines a digital display interface of a digital audio/video interconnect. The DP is intended to be used primarily between a computer and its display monitor, or a computer and a home-theater system. The DP interface is facilitated using a proprietary cable and connectors, each of which includes 20 pins. The DP cable is a cross cable, i.e., each of the source and sink connectors has a different configuration.
In a typical configuration, transport channels of a DP interface include a main link, an auxiliary (AUX) channel, and a hot plug detect (HPD) channel. The main link is a unidirectional channel that allows data transfers over up to 4 lanes; the lanes carry clock signals in addition to the video/audio streams. Each lane is an AC-coupled differential pair. The auxiliary channel is a bi-directional half-duplex channel that carries control and management information, and the HPD channel is used by a sink device to interrupt a source device when a plug is connected or disconnected.
Recently, interface standards that define the digital display interfaces of a digital audio/video interconnect for portable devices (such as smart phones, tablet computers, and the like) have been defined, one example of which is the mobile high-definition link (MHL). The MHL is a proposed industry standard for a mobile audio/video interface for the direct connection of mobile phones and other portable consumer electronics (CE) devices to high-definition televisions (HDTVs) and displays. Specifically, the MHL is an interface protocol that provides for the connection of a mobile device to an HDMI display device. A current implementation of an MHL connector is a 5-pin MHL-USB connector, which is based on a micro-USB type connector. However, the MHL connectivity does not support data transfer according to the USB protocols, but rather only MHL signaling through the connectors and over the cable that are used.
The MHL signaling includes a single transition minimized differential signaling (TMDS®) channel utilized to transfer video, audio, and auxiliary data encapsulated in TMDS characters. Such transmission is synchronized using a high-frequency clock signal running as a common mode for the TMDS channel. The TMDS channel is a differential pair channel. A MHL cable also includes a control BUS (CBUS) for sign HPD, which also carries control information.
The MHL interface supports video and digital audio while simultaneously charging the connected mobile device. With this aim, the MHL interface includes a VBUS signal originated at the sink device (e.g., digital TV) through which the mobile device is being charged. The MHL connector is the mobile device while at the sink device an HDMI connector having 19 pins is utilized.
Mobility DisplayPort™ (or MyDP) is another standard that defines an audio/video interconnect interface for mobile devices. The MyDP standard is based on the DisplayPort™. Current implementation of a MyDP connector is a 5-pin proprietary connector. The MyDP connectivity includes a main link, an auxiliary channel with a hot plug detect (AUX_HPD) channel, and a DP_PWR signal for charging a source device (e.g., a smart phone) by a sink device (e.g., a digital TV). The main link is a unidirectional channel that carries clock signals in addition to the video/audio streams. The main link is an AC-coupled differential pair (i.e., includes 2 wires). The AUX_HDP channel is a bi-directional half-duplex channel that carries control and management information. The AUX_HDP channel is also used by a sink device to interrupt a source (handheld) device when a plug is connected or disconnected.
The Universal Serial Bus (USB) standard is primarily utilized to establish communication between devices and a host controller of a PC. The USB can connect computer peripherals, such as mice, keyboards, digital cameras, printers, personal media players, flash drives, network adapters, external hard drives, and the like. The USB was designed for personal computers, but it has become commonplace on handheld devices, such as mobile phones, smartphones, PDAs, tablet computers, camcorders, and video game consoles. The USB can also serve as a power cord for charging such devices. For many types of handheld devices, the USB is the only standard interface. The various USB protocols support different transmission rates for data. For example, data transmission rates of USB 2.0 can be 1.5 Mbps (Low speed), 12 Mbps (Full Speed), and High speed (480 Mbps). The USB 3.0 standard defines a higher speed data transmission rate of 5 Gbps, and therefore can be utilized as a database for mass storage devices, and the like.
There are several types of USB connectors. The most common connectors for handheld devices are micro USB 5-pin Standard-AB plugs and receptacles. Typically, the USB connectors in the Standard-AB plug are recessed in the plug, thereby allowing the power to be connected first, thus preventing data errors by allowing the device to power up first and then transfer data. The pin out of a standard-micro USB 2.0 AB plug and receptacle is detailed in Table 1:
TABLE 1Pin NumberPin NameFunction1.VBUSPower2.D−USB 2 Diff pair3.D+4.IDAllows distinction of hostconnection from slaveconnection5.GNDGround for power returnShield
Another popular connector is a standard AB micro USB 3.0 10-pin connector, the pin out of which is provided in Table 2:
TABLE 2Pin NumberPin NameFunction1.VBUSPower2.D−USB 2 Diff pair3.D+4.IDKeying5.GNDGround for power return6.MicB_SSTX−Super speed RX diff pair7.MicB_SSTX+8.GND_DrainGround for signal return9.MicB_SSRX−Super speed TX diff pair10.MicB_SSRX+Shield
USB specifications provide a 5V±5% supply on a single wire from which connected USB devices may draw power between the positive and negative bus power lines. A unit load is defined as 100 mA in USB 2.0 and 150 mA in USB 3.0. A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0 and 6 unit loads (900 mA) can be drawn from a port in USB 3.0.
As mentioned above, the new mobile connectivity interfaces, such the MHL and MyDP, enable streaming of multimedia content (video/audio), while charging the device. However, these mobile connectivity interfaces introduce some limitations. For example, higher video resolution cannot be transferred when charging the mobile device. In addition, user data (e.g., data files, images, etc.) stored in the handheld device or in the sink device cannot be transferred using these mobile connectivity interfaces.
For example, as noted above the MHL connector is a micro USB 5-pin type connector. However, the MHL standard does not support USB signaling and data transferring. Thus, a MHL-type cable is used to stream multimedia connect, while another USB cable is required to transfer USB data.
Thus, it would be advantageous to provide a solution that would enable simultaneous power charging as well as streaming of data and multimedia signals through a single cable having a single connector in handheld devices.